Author: melifaro
Date: Sun Aug 16 12:23:58 2015
New Revision: 286825
URL: https://svnweb.freebsd.org/changeset/base/286825
Log:
Split arpresolve() into fast/slow path.
This change isolates the most common case (e.g. successful lookup)
from more complicates scenarios. It also (tries to) make code
more simple by avoiding retry: cycle.
The actual goal is to prepare code to the upcoming change that will
allow LL address retrieval without acquiring LLE lock at all.
Reviewed by: ae
Differential Revision: https://reviews.freebsd.org/D3383
Modified:
head/sys/netinet/if_ether.c
Modified: head/sys/netinet/if_ether.c
==============================================================================
--- head/sys/netinet/if_ether.c Sun Aug 16 12:09:55 2015 (r286824)
+++ head/sys/netinet/if_ether.c Sun Aug 16 12:23:58 2015 (r286825)
@@ -309,57 +309,37 @@ arprequest(struct ifnet *ifp, const stru
}
/*
- * Resolve an IP address into an ethernet address.
- * On input:
- * ifp is the interface we use
- * is_gw != if @dst represents gateway to some destination
- * m is the mbuf. May be NULL if we don't have a packet.
- * dst is the next hop,
- * desten is where we want the address.
- * flags returns lle entry flags.
+ * Resolve an IP address into an ethernet address - heavy version.
+ * Used internally by arpresolve().
+ * We have already checked than we can't use existing lle without
+ * modification so we have to acquire LLE_EXCLUSIVE lle lock.
*
* On success, desten and flags are filled in and the function returns 0;
* If the packet must be held pending resolution, we return EWOULDBLOCK
* On other errors, we return the corresponding error code.
* Note that m_freem() handles NULL.
*/
-int
-arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
+static int
+arpresolve_full(struct ifnet *ifp, int is_gw, int create, struct mbuf *m,
const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
{
- struct llentry *la = 0;
- u_int flags = 0;
+ struct llentry *la = NULL;
struct mbuf *curr = NULL;
struct mbuf *next = NULL;
- int create, error, renew;
+ int error, renew;
if (pflags != NULL)
*pflags = 0;
- create = 0;
- if (m != NULL) {
- if (m->m_flags & M_BCAST) {
- /* broadcast */
- (void)memcpy(desten,
- ifp->if_broadcastaddr, ifp->if_addrlen);
- return (0);
- }
- if (m->m_flags & M_MCAST) {
- /* multicast */
- ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
- return (0);
- }
+ if (create == 0) {
+ IF_AFDATA_RLOCK(ifp);
+ la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
+ IF_AFDATA_RUNLOCK(ifp);
}
-retry:
- IF_AFDATA_RLOCK(ifp);
- la = lla_lookup(LLTABLE(ifp), flags, dst);
- IF_AFDATA_RUNLOCK(ifp);
- if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
- && ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
+ if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
create = 1;
- flags |= LLE_EXCLUSIVE;
IF_AFDATA_WLOCK(ifp);
- la = lla_create(LLTABLE(ifp), flags, dst);
+ la = lla_create(LLTABLE(ifp), 0, dst);
IF_AFDATA_WUNLOCK(ifp);
}
if (la == NULL) {
@@ -389,10 +369,7 @@ retry:
if (pflags != NULL)
*pflags = la->la_flags;
- if (flags & LLE_EXCLUSIVE)
- LLE_WUNLOCK(la);
- else
- LLE_RUNLOCK(la);
+ LLE_WUNLOCK(la);
if (renew == 1)
arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
@@ -400,20 +377,7 @@ retry:
return (0);
}
- if (la->la_flags & LLE_STATIC) { /* should not happen! */
- log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
- inet_ntoa(SIN(dst)->sin_addr));
- m_freem(m);
- error = EINVAL;
- goto done;
- }
-
renew = (la->la_asked == 0 || la->la_expire != time_uptime);
- if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
- flags |= LLE_EXCLUSIVE;
- LLE_RUNLOCK(la);
- goto retry;
- }
/*
* There is an arptab entry, but no ethernet address
* response yet. Add the mbuf to the list, dropping
@@ -438,11 +402,6 @@ retry:
} else
la->la_hold = m;
la->la_numheld++;
- if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
- flags &= ~LLE_EXCLUSIVE;
- LLE_DOWNGRADE(la);
- }
-
}
/*
* Return EWOULDBLOCK if we have tried less than arp_maxtries. It
@@ -469,15 +428,88 @@ retry:
arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
return (error);
}
-done:
- if (flags & LLE_EXCLUSIVE)
- LLE_WUNLOCK(la);
- else
- LLE_RUNLOCK(la);
+
+ LLE_WUNLOCK(la);
return (error);
}
/*
+ * Resolve an IP address into an ethernet address.
+ * On input:
+ * ifp is the interface we use
+ * is_gw != 0 if @dst represents gateway to some destination
+ * m is the mbuf. May be NULL if we don't have a packet.
+ * dst is the next hop,
+ * desten is the storage to put LL address.
+ * flags returns lle entry flags.
+ *
+ * On success, desten and flags are filled in and the function returns 0;
+ * If the packet must be held pending resolution, we return EWOULDBLOCK
+ * On other errors, we return the corresponding error code.
+ * Note that m_freem() handles NULL.
+ */
+int
+arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
+ const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
+{
+ struct llentry *la = 0;
+ int renew;
+
+ if (pflags != NULL)
+ *pflags = 0;
+
+ if (m != NULL) {
+ if (m->m_flags & M_BCAST) {
+ /* broadcast */
+ (void)memcpy(desten,
+ ifp->if_broadcastaddr, ifp->if_addrlen);
+ return (0);
+ }
+ if (m->m_flags & M_MCAST) {
+ /* multicast */
+ ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
+ return (0);
+ }
+ }
+
+ IF_AFDATA_RLOCK(ifp);
+ la = lla_lookup(LLTABLE(ifp), 0, dst);
+ IF_AFDATA_RUNLOCK(ifp);
+
+ if (la == NULL)
+ return (arpresolve_full(ifp, is_gw, 1, m, dst, desten, pflags));
+
+ if ((la->la_flags & LLE_VALID) &&
+ ((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
+ bcopy(&la->ll_addr, desten, ifp->if_addrlen);
+ renew = 0;
+ /*
+ * If entry has an expiry time and it is approaching,
+ * see if we need to send an ARP request within this
+ * arpt_down interval.
+ */
+ if (!(la->la_flags & LLE_STATIC) &&
+ time_uptime + la->la_preempt > la->la_expire) {
+ renew = 1;
+ la->la_preempt--;
+ }
+
+ if (pflags != NULL)
+ *pflags = la->la_flags;
+
+ LLE_RUNLOCK(la);
+
+ if (renew == 1)
+ arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
+
+ return (0);
+ }
+ LLE_RUNLOCK(la);
+
+ return (arpresolve_full(ifp, is_gw, 0, m, dst, desten, pflags));
+}
+
+/*
* Common length and type checks are done here,
* then the protocol-specific routine is called.
*/
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